The present disclosure relates generally to a method of chemically altering a silicon surface and electrical devices having the chemically altered silicon surface. The present disclosure particularly relates to the creation of a dielectric material on a semiconductor device utilizing atomic layer deposition.
The shrinking of the field-effect device channel length requires an increase in the capacitance of the gate dielectric in order to achieve desired performance. There are difficulties associated with decreasing the oxide thickness in a reproducible fashion when that gate dielectric is SiO2. Leakage currents are unacceptable when the oxide thickness is less than 1.2 nm. An alternative approach has been to deposit high-k dielectrics. However, a difficulty with this approach is that, in general, these materials are mismatched with the underlying silicon lattice. This leads to formation of additional interface states, which degrades the device performance. These relatively high dielectric material display temperature sensitivity with respect to micro-crystal formation, migration phenomenon, and relatively low intrinsic dielectric constants. In addition, these materials are not easy to alter or modify.
According to one illustrative embodiment, there is provided a method of chemically altering a silicon surface. The method includes (a) reacting a halide of a first element having only one positive divalent oxidation state with a hydroxyl group bound to a silicon atom of the silicon surface so as to chemically couple the first element to the silicon atom of the silicon surface, (b) hydrolyzing a bond between a halogen atom and an atom of the first element so as to generate a hydroxyl group bound to the atom of the first element, and (c) reacting a halide of a second element that has a trigonal bipyramidal structure with the hydroxyl group bound to the atom of the first element so as to chemically couple the halide of the second element to the atom of the first element.
According to another illustrative embodiment, there is provided an electronic device. The electronic device includes a silicon substrate with an atom of an element having only one positive divalent oxidation state chemically coupled to a silicon atom of the silicon substrate. The electronic device also includes a trigonal bipyramidal moiety chemically coupled to the atom having only one positive divalent oxidation state.
According to yet another illustrative embodiment, there is provided a semiconductor device. The semiconductor device includes a dielectric material which has an atom of an element having only one positive divalent oxidation state chemically coupled to a silicon atom of a silicon substrate of the dielectric material. The semiconductor device also includes a trigonal bipyramidal moiety chemically coupled to the atom of the element having only one positive divalent oxidation state.